Peru eyes pulling Petroperu's 25 pct stake in two oil blocks -union

LIMA, March 25 (Reuters) - Peru wants to cancel state-run energy firm Petroperu's 25 percent stake in two oil blocks that it had planned to develop with conglomerate Grana y Montero, a union leader and industry insider said Wednesday.

A reversal would mark a shift in President Ollanta Humala's ambitions for Petroperu to take part in oil production for the first time in more than two decades.

Petroperu signed an agreement with Grana y Montero in February to take a 25 percent share in oil blocks 3 and 4.

"Everything was ready ... but the minister wants to take away Petroperu's opportunity to participate," said Juan Castillo, a senior leader of Petroperu's workers' union who sometimes sits on its board.

An industry insider following the discussions also said the government wanted to relinquish its stakes.

"The energy and mines minister wants Petroperu to back out of these contracts," the industry source said.

Minister Rosa Maria Ortiz, who joined the cabinet last month, told Petroperu that its partnership in blocks 3 and 4 violates legislation that requires the company to prioritize a $3.5 billion upgrade of its Talara refinery, Castillo said.

The ministry did not respond to repeated requests for comment. Grana y Montero declined to comment.

Petroperu workers scheduled a 24-hour strike on April 8 to press the government to maintain its stake, union boss Luis Lozano said. An indefinite strike is planned if the government pulls Petroperu's stakes in the two concessions, he said.

Grana y Montero won the rights to develop the blocks in December. Under a law introduced during Humala's presidency, Petroperu can control up to 25 percent of oil concessions that come up for auction.

The reform was part of Humala's bid to transform Petroperu into a bigger regional player along the lines of Brazil's Petroleo Brasileiro Petrobras or Colombia's Ecopetrol.

Humala's presidency has been tainted by erratic policymaking on energy. He has named four Petroperu presidents during his less-than four years in power, including a new one last week.

Opposition lawmaker Manuel Dammert said Grana y Montero would emerge the winner if the government offloads its stake. But the move would be illegal unless a new auction is held, he said, because a contract had been signed.

"A private company is being favored illegally to the detriment of Petroperu," Dammert said. (Additional reporting by Dante Alva; Editing by Richard Lough and Lisa Shumaker)